For his outstanding contributions to the study of the physiology of insect vision.

Roger Hardie's work provides an impressive example of how findings from one branch of science can have unpredicted benefits in distantly related fields. Insects and vertebrates have ancestors that diverged more than 500 million years ago, and although their eyes perform essentially the same function, they do so in very different ways. Both in the optical structure of the eye, and in the biochemistry of the light-transducing process, insects demonstrate a different but equally successful alternative to the vertebrate visual system.

Roger Hardie has investigated the eyes of insects, principally two-winged flies, and has made discoveries at many levels. His first studies, in 1981, were on the differences between the eyes of male and female houseflies. Male flies have a modified forward-pointing region in which the colour vision system is replaced by afaster and more sensitive system for flight control which helps them to mate on the wing. Hardie then concentrated on the conversion of light into electrical signals by the photoreceptors. One of his first findings, in 1986, was that communication between the receptors and neurons at the next level was by a simple molecule, histamine, that had not previously been considered to be aneuro-transmitter.

His work then concentrated on the transduction process itself. In vertebrates channels in the membrane close to sodium ions when light activates rhodopsin, but in insects they open, letting sodium and calcium ions in. These transient receptor potential (TRP) channels were discovered by Hardie and Minke in 1992. Hardie also introduced a new electrophysiological technique -whole cell patch-clamping -which made it possible to study the detailed properties of the TRP channel in these very small cells.Over the next decade many other aspects of the transduction process were elucidated by Hardie and his colleagues. These included asecond ion channel, the roles of inositol trisphosphate and diacyl glyceride as messenger molecules in the pathway, and the role of magnesium in light adaptation.

Remarkably, the TRP channel has tumed out to be the founder member of a novel ion channel family widely distributed in the animal kingdom. At least 20 mammalian subtypes are now known, and are involved in ion regulation in muscle cells, pheromone signalling, thermal nociceptors and capsaicin receptors. The involvement of TRP channels in pain reception has now led to clinical trials of new analgesic drugs designed to block these receptors. Hardie's contributions to the intimate processes of insect vision illustrate beautifully the way in which evolution produces diversity, but a diversity based on acommon set of molecular mechanisms that go back to the origins of animal life.